Drill bit



March 13, 1951 J. G. JACKSON DRILL BIT 2 Sheets-Sheet 1 Filed May 19,1947 awue/wroc John Gordon Jackson March 13, 1951 J. G. JACKSON DRILLBIT 2 Sheets-Sheet 2 Filed May 19, 1947 k C a J n o d r o Patented Mar.13, 1951 mam. err

John Gordon Jackson, Denver, 0010., assignor to Eastman Oil Well SurveyCompany, Denver, 0010., a corporation of Delaware Application May 19,1947, Serial No. 748,927

Claims.

This invention relates to new and useful improvements in drill bits.

The invention relates particularly to that type of drill bit, generallyknown as a trigger bit.

As is well known, trigger bits are employed in oil well drilling and areordinarily constructed of a bit body having an axial bore and providedwith exterior cutting blades which perform the drilling operation. It isusual practice to provide some means for normally closing the axial boreso as to prevent the entrance of a core up= wardly therein. When it isdesired to take a core, suitable core taking equipment is loweredthrough the bore with the core barrel of such equipment extendingoutwardly in advance of the bit. Trigger bits also have other uses suchas permitting a well survey instrument to extend outwardly through theaxial bore thereof, where-- by information as to deviation and directionof deviation may be obtained while the bit and drill stem remain in thewell bore.

1 through the bore of the bit when the core-break.-

It is one object of the present invention to provide an. improvedtrigger bit which is constructed so that during the normal drilling operation, the circulated drilling fluid is utilized to the maximumextent, whereby efiicientdrilling. is assured; said bit also havingmeans which will permit core taking or other apparatus to extendtherethrough and in advance thereof.

It is another object of the invention to provide an improved drillingbit of the trigger type which is provided with an axial bore and whichhas improved means for normally substantially closing said bore toprevent the admission of a core during normal drilling operations.

An important object of the invention is to provide an improved triggerbit having the usual exterior cutting blades and also having pivotedcore-breaking blades which normally swing inwardly to substantiallyclose the axial bore extending through the bit; the pivotedcore-breaking blades being readily movable to an outer position wherebya well survey instrument or other apparatus may be moved downwardlythrough the bore to extend in advance of said bit.

Another object of the invention is to provide an improved trigger bit,of the character described, wherein the pivoted core-breaking blades areformed with deflector elements which, when the blades are in theirinward or closed position,

substantially close the axial bore through the bit to restrict the flowof the drilling fluid, whereby said fluid is caused to be directed ontothe main cutting blades under a relatively high velocity;- saiddeflector elements being so constructed that ing blades are in theirouter or extended position.

A still further object of the invention is to provide a trigger bit, ofthe character described, wherein the deflector elements which substantially close the bore of said bit are disposed in such a manner withrespect to the main cutting blades of the bit that any fluid whichescapes from the lower end of said bore, past said ele-- ments isdirected into immediate contact with said cutting blades, wherebyeflicient lubrication of the bit is assured The construction designed tocarry out the invention will be hereinafter described together withother features of the invention.

The invention will be more readily understood from a reading of thefollowing specification and by reference to the accompanying drawing,wherein an example of th invention is shown, and wherein:

Figure 1 is an elevation of a drilling bit constructed in accordancewith the invention,

Figure 2 is an elevation of the bit taken at a right angle to theposition shown in Figure 1,.

Figure 3' is a transverse, vertical, sectional view taken on the line3-3 of Figure 1.,

Figure 4 is a view similar to Figure 3- illustrating the core-breakingblades swung to their outward position,

Figure 5 is a transverse, vertical, sectional view taken on the line 55of Figure 2,

Figure 6 is a horizontal, cross-sectional View taken on the line 66 of.Figure 1, and

Figure '7 is an isometric view of the corebreaking blades illustratingthe deflector elements associated therewith.

In the drawings, the numeral Iii designates a bit body which isgenerally cylindrical in crosssection and which. is gradually reducedtoward its lower end. The upper end of the body has an internallythreaded box. H made integral therewith and. this box is of standard.construction for receiving the lower end of the drill pipe or sub (notshown). Diametrically opposed cut ting blades 12 are formed integralwith the body it) and extend outwardly in a radial direction. Eachcutting blade is provided with a sharpened lower cutting edge It and theforward or cutting surface i2a of each blade extends in substantiallythe same longitudinal plane as the axis of the body iii. The rearportion of each blade is, suitably reinforced by an enlargement [2bwhich is integral with the bit body. When the bit is rotated, the maincutting blades l2 perform the digging operation in the usual manner.

Extending downwardly from the threaded box H is an axial bore it whichpasses entirely through the bit body and has its lower end open, wherebydrilling fluid circulated downwardly may be ejected from the lower endof said bore. Inclined upper ports l5 may extend from the upper end ofthe bore It to a point adjacent the upper end of the forward surface ofeach main cutting blade I2 but if desired, these ports may be omitted.Similar lubricating passages it which may be formed by cutting ormilling a recess in the wall of the body adjacent the lower end of thebore also establish communication between the bore and the forward facel2a of the blades. With the provision of the ports, 25, circulation offluid downwardly through the bore it causes some of the fluid to beejected outwardly through said ports and also through the passages 16onto the faces 12a of the cutting blades, whereby said blades arelubricated and also whereby the cuttings which are removed from theformation by the blades are circulated to the surface.

Diametrically opposed longitudinal ribs H are formed integral with thebit body (0 and these ribs are disposed at substantially a right angleto the diametrically opposite main cutting blades Ill. The lower end ofeach rib is bifurcated to form depending ears l8 between which ispivoted a core-breaking blade l9. As is clearly illustrated in Figure 7,each core-breaking blade includes the blade portion 23 which has anupstanding extension or lug 2i preferably made integral therewith. Thelug has a transverse opening 22 which aligns with complementary openings23 in the ears l8 and a pivot pin 24 mounts each blade on the bit. Whenswung inwardly, the blade portion 2i} of each core-breaking bladeoverlies the open lower end of the bore M of the bit body. Because thelug 2| extends upwardly above the blade portion of each corebreakingblade it, a shoulder or flat surface 25 is formed by the top of saidblade portion and when the blades are swung to their inward position,the shoulders or surfaces 25 are located immediately below the openlower end of the bore M.

For restricting the area of the bore M so as to setup a back pressureand cause the drilling fluid to be ejected forcibly through the inclinedports :5 and passages I6 onto the forward surfaces of the main cuttingblades and also for deflecting anyfluid escaping from the lower end ofthe bore onto said blades, each core-breaking blade isformed with adeflector element or plate 26. Each element or plate is secured in anysuitable manner to the shoulder or surface 25 of its blade is and as isclearly illustrated in Figure l, the plates 26 are inclined in oppositedirections from a horizontal plane when the corebreaking blades 19 arein their inward position. Thus, when the blades is are swung inwardlybeneath the open end of the bore 14 of the bit, the deflector elementsor plates are disposed immediately below said open end. These plates areof such area as to substantially close this lower end of the bore and,therefore, when in an inward position any circulation of fluiddownwardly through the bore is restricted by said deflector elements;this restriction of circulation sets up a back pressure within the bore14 which causes the fluid to be forcibly ejected under a relatively highvelocity through the inclined ports l5 and passages l6 onto the forwardor cutting faces [2a of the main cutting blades. Because the deflectorplates or elements do not completely close the bore, some fluid willescape from the lower end thereof and this escaping fluid is properlydirected against the cutting blades by the inclination of the deflectingelements. It is noted that the inclination of one of the deflectingplates 26 is such that a portion of the circulating fluid escaping fromthe bore M is directed against one of the main cutting blades l2, whilethe disposition of the other blade directs the remainder of said fluidagainst the second cutting blade. Thus, it becomes obvious that thecirculating fluid is forced into direct contact with the cutting blades12 through the ports 55, passages 16 and by means of the inclineddeflector blades. In this manner, ample lubrication of the main cuttingblades i2 is assured and also the washing-up of the cuttings removed bythe main blades i2 is carried out.

In the operation of the bit, the main blades 52 perform the drillingoperation and the pivoted smaller blades 19 merely function to break thecore which would normally move upwardly within the bore 1 3. Therefore,under normal drilling, the core-breaking blades i9 are in substantiallythe position shown in Figure 3, that is they are moved inwardly. Anytendency of the blades to move to an outward position will be restrictedby the engagement of the lower end of said blades with the formation andin such position, the deflector plates 25 substantially close the lowerend of the bore. So long as the fluid circulated through the bore isrestricted, assurance that the fluid will be directed outwardly throughthe ports IS and passages l6 under a relatively high velocity is had. Ofcourse, the disposition of the deflector plates is important because itdefinitely utilizes the fluid which does escape from the lower end ofthe bore for lubricating and washing the surfaces of the main cuttingblades.

When it is desired to run a survey instrument or other apparatus throughthe bore M of the bit it is only necessary to lift said bit off bottomand then run said apparatus through said bore. The apparatus uponstriking the deflector plates 26 will swing the core-breaking blades [9outwardly to the position shown in Figure 4. In this position, theblades are moved completely out of alignment with the bore 14 to therebypermit the well survey instrument or other apparatus to extend outwardlyin advance of the bit.

From the foregoing it will be seen that a very simple and efficienttrigger type bit is provided. The core-breaking blades are normally inan inward position during the drilling operation and in such position,the deflector plates 28 function to break the core and also tosubstantially close the bore [4 to restrict-the circulation of fluidtherethrough. As has been stated, this restriction of the circulatingfluid assures that the major portion of the fluid will be forcedoutwardly under a relatively high velocity through the ports l5 andpassages I6. The remaining fluid which escapes past the deflector plates26 is, because of the inclination or disposition of said plates, forceddirectly into contact with the cutting faces I211 of the cutting blades12. With this arrangement all of the fluid which is circulated isutilized to the fullest extent in lubricating and washing the bitblades, whereby balling up of the bit is definitely prevented. Thedeflector plates are so arranged that they do not interfere with theopening of the core-breaking blades to permit the running of a wellsurvey instrument or other apparatus through said bit.

As has been noted, the inclined circulation ports I5 may be omittedwithout interfering with efficient operation of the bit; in suchinstance,

the circulation downwardly through the bore 14 will be forced outwardlythrough passages I6 and the spaces around the deflector elements andalthough the volume of fluid in, this case is not asmuch as when theports l5 are provided, yet said volumeis sufficient to properlylubricate the blades and to wash the" cuttings to the'surface.

The foregoing description of the invention is explanatory thereof andvarious changes inthe size, shape and materials, as well as in thedetails of the illustrated construction maybe made, within the scope ofthe appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A drill bit including, a body having an axial bore extendingtherethrough, main cutting blades on the exterior of said body,circulating passages extending from thebore of the body to the blades,

whereby fluid circulated downwardly through the bore may flow throughsaid passages and onto the blades to lubricate and wash the same,corebreaking blades pivotally mounted on the lower portion of the bodyand arranged to swing inwardly beneath the open lower end of the bore,and means on said core-breaking blades for establishing a wall areaacross the open end of the bore substantially equal to the crosssectional area of the bore and thereby restrict the flow of fluidthrough the bore when said blades are in their inner positions, wherebya back pressure is built up within the bore and fluid is forciblyejected under relatively high velocity through the circulating passagesonto the main cutting blades to assure eflicient lubrication and washingthereof.

2. A drill bit including, a body having an axial I bore extendingtherethrough, main cutting blades on the exterior of said body,circulating passages extending from the bore of the body above its loweropen end to the blades, whereby fluid circulated downwardly through thebore may flow through said passages and onto the blades to lubricate andwash the same, core-breaking blades pivotally mounted on the lowerportion of the body and arranged to swing inwardly beneath the openlower end of the bore, and means on said core-breaking blades forforming a wall of an area substantially that of the bore across thelower open end of the bore for restricting the flow of fluid through thebore when said blades are in their inner positions, whereby a backpressure is built up within the bore and fluid is forcibly ejected underrelatively high velocity through the circulating passages onto the maincutting blades to assure efiicient lubrication and washing thereof, saidlast-named means also functioning to deflect the fluid which isdischarged from the lower end of the bore outwardly at a sharp angle tothe bore axis and against the main cutting blades.

3. A drill bit including, a body having an axial bore extendingtherethrough, main cutting blades on the exterior of said body,circulating passages extending from the bore of the body to the blades,whereby fluid circulated downwardly through the bore may flow throughsaid passages and onto the blades to lubricate and wash the same,core-breaking blades pivotally mounted on the lower portion of the bodyand arranged to swing inwardly beneath the openlower end of the bore,and a deflector element in the form of a plate mounted on eachcore-breaking blade, said elements being located tobecome positioned toform a wall below and extending substantially across the open lower endof the bore of the bit body when the core-breaking blades are in theirinner position, whereby saidelements restrict flow through said bore andassure the ejection of a circulating fluid outwardly throughthecirculating passage under a relatively high velocity to assureeflici'ent washing and lubrication of the maincutting blades.

4. A drill bit including, a body having an axial bore extendingtherethrough, main cutting blades on the exterior of said body,circulating passages extending fromthe bore of the body to the blades,whereby fluid circulated downwardly through the bore may flow throughsaid passages and onto the blades to lubricate and wash the same,core-breaking blades pivotally mounted on the lower portion of the bodyand arranged to swing inwardly beneath the open lower end of the bore,and a deflector element mounted on each core-breaking blade, saidelements being located below and extending substantially across the areathe open lower end of the bore of the bit body when the core-breakingblades are in their inner position, whereby said elements restrict flowthrough said bore and assure the ejection of a circulating fluidoutwardly through the circulating passage under a relatively highvelocity to assure efllcient washing and lubrication of the main cuttingblades, said elements being disposed at an angle from a horizontal planewith the particular disposition being such that the fluid dischargedfrom the open lower end ,of the bore is directed outwardly at a sharpangle against the faces of the main cutting blades.

5. A drill bit as set forth in claim 1, wherein the means forrestricting the flow through the bore comprises flat deflector plateswith one plate mounted on each core-breaking blade.

6. A drill bit as set forth in claim 4, wherein the deflector elementscomprise flat plates and also wherein one of the plates is inclined inan opposite direction from a horizontal plane to the inclination of theother plates, whereby each plate deflects a portion of the circulatingfluid discharging from the lower end of the bore onto one of the maincutting blades.

7. The combination with a drill bit having a bit body provided withexterior main cutting blades with radially extending faces projectil'lgupwardly alongside the bit body and having an axial bore with fluidcirculating passages extending from the bore to the face of said blades,of a pivoted plate restricting means mounted to swing upwardly from apoint below the bottom end of the bore to an inner position to form wallmeans beneath the lower end of said bore of an area substantially thecross sectional area of the bore, whereby flow through said bore may berestricted to assure ejection of circulating fluid from the circulatingpassages at a relatively high velocity.

8. The combination with a drill bit having a bit body provided withexterior main cutting blades and having an axial bore with fluidcirculating passages extendin from the bore to the face of said blades,of a pivoted plate restricting means mounted to swing upwardly from apoint below the bottom end of the bore to an inner position beneath thelower end of said bore and thereby establish beneath said end a wallhaving an area substantially .the cross sectional area of the bore,whereby flow through said bore may be restricted to assure ejection ofcirculating fluid from the circulating passages at a relatively highvelocity, said restricting means also functioning to deflect the fluiddischarging from the well bore into direct contact with the surfaces ofthe main cutting blades adjacent and below the bottom end of the bore.

9. A drill bit including, a body having an axial bore extendingtherethrough, two main cutting blades on the exterior of said body,circulating passages extending from the bore of the body to the blades,whereby fluid circulated downwardly through the bore may flow throughsaid passages and onto the blades to lubricate and wash the same, twocore-breaking blades pivotally mounted on the lower portion of the bodyand disposed at substantially a right angle to main cutting blades, saidcore-breaking blades being adapted to be swung from an outer positioncompletely out of alignment with the bore of the bit body to an innerposition beneath said bore, and a deflector plate element secured toeach core-breaking blade, said plate elements being so disposed thatwhen the blades are in an inner position they co-act with each other tosubstantially close the lower end of the bore to restrict the flowtherethrough and thereby assure ejection of the circulatin fluid fromthe circulating passages under a relatively high velocity, the deflectorplate elements being posi- Vbcre extending therethrough, main cuttingblades on the exterior of said body, core-breaking blades pivotallymounted on the lower portion of the body and arranged to swing inwardlybeneath the open lower end of the bore, and means on said core-breakinblades for restricting the flow of fluid through the bore when saidblades are in their inner positions, said restricting means also beingso constructed as to function to deflect in volume the fluid which isdischarged from the lower end of the bore laterally at a sharp angle andagainst the main cutting blades.

JOHN GORDON JACKSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 144,475 Phillips et a1. Nov. 11,1873 1,542,172 Reed et a1. June 16, 1925 2,179,010 Creighton et al Nov.7, 1939

